Telegraph system



Nov. 24, 1925. 1,562,943

G. c. CUMMINGS TELEGRAPH SYSTEM Filed June 30, 1924 W re/72W:- aearye away/Why; 4/ 4/7].-

Patented Nov. 24, 1925.

i if? ti PTENT OFFICE.

C, CUIJII'X'L'INGS, O3? ORANGE, NEW JERSEY, ASSIGNDR TO WEtiTERN ELECTRIC COLEFANY, INCGEEOBAEED, OF NEW N. Y., A CORPORATION OF NEW YORK.

TELEGBAEH SYSTEM.

Application filed June 30, 19%. Serial No. @3142.

To (all 10710. 21 2'1- mc-g (once r11 Be it known that it. (in non G. Continues, a subject of the King of Great Britain, residing at Orange, in the county of Essex, State of New Jersey, have invented certain new and useful improvements in Telegraph Systems, of which the -iiollowing is a full, clear, concise, and exact description.

This invention relates to duplex telegraph systems.

The invention may be arranged for duplex operation, that is, transmission in both directions sil'nultaneously, but preferably it is adapted to halt-duplex operation in which the impulses are trai mitted one way at a time. Heretotore, in operating metallic circuit systems halt-duplex, it has been the practice to operate the loop circuit as a balanced duplex which does not readily lend itself to the connection o'l three or more circuits to operate halt-duplex in several directions out of one ottice. In the use of such systems in which the transmission of the impulses results from the application of currents of positive and negative polarity, considerable ditiiculty has been experienced when the systemis utilized with a number oi way-stations. With this type of system a number of relays are necessarily connected in series, and, in consequence, considerable inductive discharge through the balancing network results, which. is suliicient to destroy the relay adjustment. It is therefore neces sary, when .itv desired to receive or transmit. to change the adjustu'ient of the relays to correct :t'or this unbalanced condition in H'tltil to receive and transmit correct signals.

l t the object of thepresent invention to obviate the ditticulties heretofore encountered by arranging the system to cause the tnnsmission o'tcurrent reversals on the metallic circuit, while in the case of the loop circuit the circuit is actually opened and closed.

According to the preferred term, the invention provides a metallic line circuit equipped with what is commonly referred to as a vibrating relay operating to im- 11 impulses of both polarities on a local circuit. 'Connected in this local circuit and responsive to the positive and negative current impulses, is a relay which functions to make and break the loop circuit, whereby the signals receivec 'tfrom the line will be retransu'iittcd to the station connected thereto. By having other relays connected in the local circuit but arranged to be unresponsive to the operation of the vibrating relay, impulses may be transmitted from the loop circuit to the metallic line circuit, and thence to the connected stations.

A better understanding of the invention may be had from the following description, taken in conjunction with the accompanying drawlng, in which one embodiment of the invention is illustrated.

In the single figure of the drawing, a pair of line conductors 56 constituting a metallic line circuit terminate at a station in the windings of a vibrating relay 7, which are 1n turn connected to the respective terminals oi an artificial line and which form the anus of a duplex bridge. The vibrating relay T comprises operating windings 8 and 9, and opposing and accelerating windings 10. This type of relay is commonly referred to as the Gulstad vibrating relay, and is also arrangedwith a condenser 11 and resistance 12. When the armature of this relay engages either of its opposing contacts,a circuit is established for charging the condenser 11 in a direction depending upon the polarity of the current applied through the engaged contact. Normally, the current in the main line winding is opposed by-the current I? in the opposing windin so that the mag netic effect produced by either of these windings predominates. In other words, the magnetic eiiect of one is partly neutralized by the other. However, upon the reception Ofli a signal, the current in the opposing winding predominates in which case the armature is caused. to move from the engaged contact. from the engaged contact, the charge on the condenser 11, resulting from the engagement of the armature with the previously engaged contact, discharges through the accelerating winding 10 and the resistance 12 to ground. The movement of the armature is thereby accelerated to its opposite contact, after which a circuit is established for causing the condenser to assume a charge in accordance with the polarity oi the source of current applied through the then engaged contact.

The armature oi the vibrating relay 7 is connected to a local circuit in which there is included a plurality of relays, namely, a loop control relay 18, a break relay l9 and a pole changing or sending relay 20. For

The instant the armature moves monitoring purposes theie is also connected in this local circuit a polarized sounder 15 which responds to the reversals of the armature oi the vibrating relay 7 for recording -the signals repeated to the local circuit.

tance 28, which functions to electrically bias these relays. The purpose of providing this biasing arrzngement is to correct for differences in ground potentials. However, the relays could be equipped with mechanical means "for accomplishing the same purpose.

Extending from the contact of the loop control relay 18 is a loop circuit 24', which has connected therein asounder 25 and a trausn'iitting key 26. l

in order to permit the connection of several stations which are provided with the same equipment and which desire to receive the same messages transmitted over the metallic circuit 5, (l, the loop circuit terminates in a pair of jacks 28 and 29. Duplicate equipment, represented by the rectangle 30, may be connected with the loop circuit by the insertion of the plugs 31 and 32 in their respective jacks. 'By completing the connection of these plugs with their respective jacks, the continuity of the circuit is extended to include the duplicate equipment 30, which is located at a different station. Similarly,-other stations could be connected to the metallic circuit.

The operation of the system will now be described Assume, for the sake ofillustration. that in'ipulscs are being impressed at the distant end of the metallic circuit 5, 6. These impulses, upon being received, pass through the main line windings 8 and 9 to the artificial line AL. The ell ect of these currents is such as to produce a magnetic e'llect which PtQtlOli'lllltliQS over that produced by the opposing winding 10, and in consequence the armature of the relay 7 is caused to disengage the uppermost contact. Accordingly, the condenser '11, which was previously charged negatively, discharges through the winding 10 and the resistance 12 to ground, and accelerates the movement of the armature to its positive contact. lVhcn the armature ot the relay T is in engagement with its negative contact, current flows from the source of current connected with the resistance 17, through this resistance 17, resistance 16, armature and upper contact of the relay 7 to the negative pole of the source of current. Also, current flows through the windings oi the relays 18.19

the position shown in the drawing. The relays 19 and 20 are, however, prevented from maintaining their contacts open when the armature oi the relay 7 is engaged with the negative pole of battery because of the current flowing from the battery 34, contact of the jack 29, key 26, sounder 2-5, loop circuit contact and armature of relay 18, right iand windings of relays 19 and 20, contact of jack 28 to the negative pole of the battery. The current flowing in the circuit just traced produces a magnetic eflect which predominates over that produced by the current flowing in the circuit including the left hand windings of the relays 19 and 20, whereby these relays are prevented from maintaining their contacts open so that in consequence the contacts remain .in the position shown. Upon the reversal of the armature of relay 7 and the engagement thereof with the contact connected with the positive pole ofthe battery, the current in the circuit including the windings ot the relays 18, 19 and 20 reverses and is increased to a value such as to cause the movement of the armature of the relay 18, The current through the windings of the relays 19 and 20 is, however, in a direction to aid the current flowing from the batery 34 through the right hand windings of these relays, and their armatures therefore remain in the position shown in the drawing. Due to the operation of the relay 18, the loop circuit 2-1 is opened and impulses are repeated therein for causing the operation of the sounder The contacts 0'! the relay 18 are bijidged with a condenser 21 and a resistance for nullitying the detrimental sparking cliect produced upon the opening and closure oi.

the contact of this relay. Likewise, the contacts of the relay 7 may be bridged with a condenser and resistance .lor al'isorbing the sparking produced upon the operation of its armature. sistance in this manner not only eliminates to a considerable degree the sparking, but also tends to StflblllZ the. balance, thereby creating more satisfactory operating conditions.

Should the key 26 ,be opened slightly ahead of the disengagement of the armature of relay 7 with the contact associated with the negative pole oi'the battery, or be opened simultaneously therewith, the loop circuit will be opened and the current flowing The use 01 a condenser and rethrough the left hand windings of the relays 19 and 2-0 will be sufficient to cause the reversal ol? their armatures or to assume a position opposite to that shown in the draw ing. The relay 19, in operating, short circuits the contacts of the relay 18 and extends the loop circuit through to the relay 20, thereby permitting the control of this relay from the key 26. New, should the relay 1S operate, the loop circuit will be closed irrespective ot its operation through the contact and armature of relay 19. The reversal of the armature out relay 2O impresses on the circuit an impulse of a positive polarity, which, upon being received at the distant station or the station to which the metallic circuit 5, 6 extends, will constitute a break signal, indicating to the operator thereat that the party on the loop circuit desires to reverse the direction of sending. In this same manner, when it is desired to transmit by the operation of the key 26 which opens and closes the loop circuit Let, the pole changing relay 20 will follow the niovenient of the key 26 for transmitting over the metallic circuit 5, 6 impulses of positive and negative polarity.

It is seen from the previous description that should the key 26 be operated for trans'- mitting a break signal simultaneously with the operation of the vibrating relay '7, due to an incoming impulse, the loop circuit will not be left open, thereby preventing the operator on the loop circuit from gaining control of the circuit, this being accomplished by the provision of the relay 19,

which short circuits the contacts of the re lay 18 and extends the loop circuit to the windings of these relays.

Although the invention has been disclosed and described with reference to a particular system, it is of course obvious that various departures and modifications may be made without departing from the spirit and scope of the invention.

hat is claimed is:

1. In a telegraph system, a metallic circuit, a local circuit, signal responsive means connected in said metallic circuit for impressing on said local circuit positive and negative impulses, a loop circuit, means included in said local circuit for repeating to the loop circuit open and closed circuit conditions in accordance with the positive and negative current impulses impressed on said local circuit by said signal responsive means, and a sending relay in said local circuit.

2. In a telegraph system, a signaling path, a local circuit, a vibrating relay responsive to reversals of currentimpulses impressed on said signaling path for applying corresponding impulses to said local circuit, a loop circuit, means included in said local circuit for opening and closing said loop circuit in accordance with reversals of impulses impressed on said local circuit, and a relay in said local circuit for sending signals over said path.

3. In a polarized duplex telegraph sys tem, a signaling path, an electro-responsive device connected in said signaling path and responsive to reversals of signal. currents for repeating corresponding signals to a local circuit, a loop circuit, means responsive to the reversals of current in said local circuit for making and breaking said loop circuit, and a relay included in both the local and loop circuits for sending signals.

41:. In a telegraph system, a signaling path, a signal means associated with said signaling path and responsive to positive and negative impulses tor repeating corresponding impulses to a local circuit, a control, a break and a pole-changing relay each having a winding includedin said local circuit, a loop circuit, additional windings on the two last mentioned relays included in said loop circuit, said control relay being operated to open and close said loop circuit in accordance with the operation of said signal means, and means associated with said other relay for preventing its operation due to the opening of said loop circuit by said control relay.

5. In a telegraph system, a metallic line circuit, a local circuit, a vibrating relay con nected in said line circuit and responsive to impulses oit positive and negative polarity for repeating corresponding impulses to said local circuit, a plurality of relays each having a winding included in said local circuit, a loop circuit, additional winding on two of said relays connected in said loop circuit, one of said relays being operated to open and close said loop circuit, and means included in said local circuit for preventing the operation of the two relays which have windings connected in the loop circuit upon the reversal of said vibrating relay.

(5. In a telegraph. system, a nu-wtallic line circuit, a local circuit, a vibrating relay connected in said line circuit and responsive to lll'lI'ElllSGS oi positive and negative polarity tor repeating corresponding impulses to said local circuit, a control, a break and a pole-changing relay each. having a winding included in said local circuit, a loop circuit, additional windings on the two last mentioned relays connected in said loop circuit, means included in said local circuit tor preventing the operation of said break and pole-changing relay on the reversal of said vibrating relay, a transn'iitting key connected in said loop circuit, and circuit connections effective upon the simultaneous operation of said key and the reversal of said vibrating relay for establishing the continuity of said loop circuit independent of said control relay.

7. In a telegraph system, a metallic line circuit, a local circuit, a vibrating relay con nected in said line circuit and responsive to impulses of positive and negative polarity for repeating corresponding impulses to said local circuit, a control, break and pole changing relay each having a winding included in said local circuit, a loop circuit, additional windings on the two last mentioned relays connected in said loop circuit, means included in said local circuit for preventing the operation of said break and polechanging relay on the reversal of said vihrating relay, a transmitting key connected in said loop circuit, and circuit connections effective upon the simultaneous operation of said key and the reversal of said vibrating relay for short circuiting the contacts o't said control relay whereby the loop circuit is maintained closed. I

In Witness whereof. I hereunto subscribe my name this 25th day of June A. l), 1924.

GEORGE CUMMING F. 

